A conventional delimber of the general type this invention is concerned with is illustrated in Hamby, Jr. U.S. Pat. No. 4,899,794. There it will be seen that a cutter head assembly is mounted in a support yoke for pivotal movement about a horizontal axis relative to the yoke. In turn, the yoke includes a base plate which is mounted for rotational movement about a vertical axis on a horizontal support frame. The yoke base plate is supported for this rotation on an annular bearing adjacent the front end of the delimber. Adjacent the rear end of the delimber a pair of support rollers fastened to the bottom of the yoke base plate ride on the top surface of the support frame in an arc to support the yoke and cutter head assembly as they rotate during delimber operation.
With delimbers of this type, it is conventional to provide some kind of vertical adjustment capability for the aforedescribed support rollers. Current technology in general use is to mount rollers on the support frame, rather than on the yoke base plate as is shown in the Hamby, Jr. '794 patent delimber. This technology involves support rollers that are vertically adjustable to assure positive contact with the bottom surface of the yoke base plate. Adjustment is conventionally effected through the use of four vertical bolts, one on either side of each of two rollers. The bolts are fixed in place by jam nuts which are tightened against the roller housing. These bolts must be accessed from underneath the delimber support frame, and are threaded inward to raise a roller and outward to lower the roller. Careful attention must be given to adjusting each of the bolts equally to ensure parallel contact between the roller and the bottom surface of the yoke base plate because operation with one side of a roller higher than the other will result in uneven wear of the roller, roller bushings, and the mating yoke base plate surface.
Adjustment is made difficult because access to the bottom of the base frame is commonly obstructed due to cut limbs and other debris that build up around the delimber on the job site. Furthermore, knowing when individual roller height has been properly adjusted is also a problem because the area of contact between the yoke base plate and a roller is not readily visible to the operator from the adjustment area.
Recently a new and improved roller support system for the cutter head assembly and yoke in a tree delimber was invented by the applicant in the present application. That system is described and illustrated in the aforementioned provisional U.S. Patent Application Ser. No. 60/644,046, the disclosure of which is incorporated herein by reference.
The provisional U.S. patent application discloses a roller support system which is much easier for an operator to adjust then previously known systems. The system's rollers each require manipulating only a single adjustment screw. The adjustment screw for each of two rollers is readily accessible to the delimber operator. Adjustment remains a manual operation, however.